3D Geometry, Shape and Space - June 2004, All Stages

Problems

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Shadow Play

Stage: 1 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Here are shadows of some 3D shapes. What shapes could have made them?

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Building Blocks

Stage: 2 Challenge Level: Challenge Level:1

Here are some pictures of 3D shapes made from cubes. Can you make these shapes yourself?

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Right or Left?

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

Which of these dice are right-handed and which are left-handed?

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A Chain of Eight Polyhedra

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

Can you arrange the shapes in a chain so that each one shares a face (or faces) that are the same shape as the one that follows it?

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Cut Nets

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

Each of the nets of nine solid shapes has been cut into two pieces. Can you see which pieces go together?

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Painted Cube

Stage: 3 Challenge Level: Challenge Level:1

Imagine a large cube made from small red cubes being dropped into a pot of yellow paint. How many of the small cubes will have yellow paint on their faces?

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Triangles to Tetrahedra

Stage: 3 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Starting with four different triangles, imagine you have an unlimited number of each type. How many different tetrahedra can you make? Convince us you have found them all.

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Tetrahedra Tester

Stage: 3 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

An irregular tetrahedron is composed of four different triangles. Can such a tetrahedron be constructed where the side lengths are 4, 5, 6, 7, 8 and 9 units of length?

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Cubic Rotations

Stage: 4 Challenge Level: Challenge Level:1

There are thirteen axes of rotational symmetry of a unit cube. Describe them all. What is the average length of the parts of the axes of symmetry which lie inside the cube?

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Floating in Space

Stage: 4 Challenge Level: Challenge Level:2 Challenge Level:2

Two angles ABC and PQR are floating in a box so that AB//PQ and BC//QR. Prove that the two angles are equal.

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Far Horizon

Stage: 4 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

An observer is on top of a lighthouse. How far from the foot of the lighthouse is the horizon that the observer can see?

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Mesh

Stage: 5 Challenge Level: Challenge Level:1

A spherical balloon lies inside a wire frame. How much do you need to deflate it to remove it from the frame if it remains a sphere?

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Air Routes

Stage: 5 Challenge Level: Challenge Level:2 Challenge Level:2

Find the distance of the shortest air route at an altitude of 6000 metres between London and Cape Town given the latitudes and longitudes. A simple application of scalar products of vectors.

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V-P Cycles

Stage: 5 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Form a sequence of vectors by multiplying each vector (using vector products) by a constant vector to get the next one in the seuence(like a GP). What happens?